How should I understand the instrument symbols related to the automation field in the drawings?
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How should one interpret the gauges indicated in green? What do the letters and numbers represent?
Is there any material available that describes this instrument?
HG/T 20505 Functional indicators and graphic symbols for process measurement and control instruments
It’s available on the forum; you can search for it there, or you can use Baidu to find it as well
The dashed line from PI-1201-5 leads to two control valves; it is clearly a control system, and it should at least be labeled as PIC-1012-5, so this diagram is incorrect.
PI-1201-5 is a pressure transmitter; the PG next to it is an on-site pressure gauge. The green dashed line connecting the pressure transmitter to HV-1201-5 and KV-1202-5 indicates that this transmitter is connected in the circuit diagram to these two devices for control purposes – for example, the valve operates when the pressure value exceeds a certain level. TI-1201-5 is a temperature transmitter or thermistor; in any case, it is used for transmitting temperature values over distance. Specifically, on the PID home page there is usually a table with corresponding English letters, such as P for pressure, I for indication, and so on; valves are also indicated in the legend. These days, the design institutes don’t draw things in a standard way anyway – we just need to understand the meaning when carrying out the construction on site; P
TI temperature display, PG on-site pressure gauge, KV and HV control valves; the green dashed line indicates the control circuit